922 CANADIAN JOURNALOF ANESTHESIA
Purpose: The purpose of this narrative review is to summarize the evidence derived from randomized controlled trials (RCTs) regarding approaches and techniques for lower extremity nerve blocks.
Source: Using the MEDLINE (January 1966 to April 2007) and EMBASE (January 1980 to April 2007) databases, medical subject heading (MeSH) terms “lumbosacral plexus”, “femoral nerve”, “obturator nerve”, “saphenous nerve”, “sciatic nerve”, “peroneal nerve” and “tibial nerve” were searched and com-bined with the MESH term “nerve block” using the operator “and”. Keywords “lumbar plexus”, “psoas compartment”, “psoas sheath”, “sacral plexus”, “fascia iliaca”, “three-in-one”, “3-in-1”, “lateral femoral cutaneous”, “posterior femoral cuta-neous”, “ankle” and “ankle block” were also queried and combined with the MESH term “nerve block”. The search was limited to RCTs involving human subjects and published in the English language. Forty-six RCTs were identified.
Principal findings: Compared to its anterior counterpart (3-in-1 block), the posterior approach to the lumbar plexus is more reliable when anesthesia of the obturator nerve is required. The fascia iliaca compartment block may also represent a better alternative than the 3-in-1 block because of improved efficacy and efficiency (quicker performance time, lower cost). For blockade of the sciatic nerve, the classic transgluteal approach constitutes a reliable method. Due to a potentially shorter time for sciatic nerve electrolocation and catheter placement than for the transgluteal approach, the subgluteal approach should also be considered. Compared to electrolocation of the pero-neal nerve, electrostimulation of the tibial nerve may offer a higher success rate especially with the transgluteal and lateral popliteal approaches. Furthermore, when performing sciatic and femoral blocks with low volumes of local anesthetics, a multiple-injection technique should be used.
Conclusions: Published reports of RCTs provide evidence to formulate limited recommendations regarding optimal approaches and techniques for lower limb anesthesia. Further well-designed and meticulously executed RCTs are warranted, particularly in light of new techniques involving ultrasonographic guidance.
CAN J ANESTH 2007 / 54: 11 / pp 922–934
Objectif : L’objectif de cet examen narratif est de résumer les données probantes dérivées d’études randomisées contrôlées (ERC) concernant les approches et techniques pour les blocs nerveux du membre inférieur.
Source : A l’aide des bases de données MEDLINE (janvier 1966 à avril 2007) et EMBASE (janvier 1980 à avril 2007), les termes MeSH (vedette-matière médicale) « lumbosacral plexus », « femoral nerve », « obturator nerve », « saphenous nerve », « sciatic nerve », « peroneal nerve » et « tibial nerve » ont été recherchés et combinés au terme MeSH « nerve block » à l’aide de l’opérateur « and ». Les mots clés « lumbar plexus », « psoas compartment », « psoas sheath », « sacral plexus », « fascia iliaca », « three-in-one », « 3-in-1 », « lateral femoral cutaneous », « posterior femoral cutaneous », « ankle » et « ankle block » ont également été recherchés et combinés au terme MeSH « nerve block ». La recherche a été limitée aux ERC impliquant des sujets humains et publiées en langue anglaise. Quarante-six ERC ont été identifiées. Constatations principales : Par rapport à son équivalent antérieur (bloc 3-en-1), l’approche postérieure du plexus lombaire est plus fiable quand une anesthésie du nerf obturateur est requise. Le bloc du compartimentde l’aponévrose iliaque pourrait également représenter une meilleure alternative que le bloc 3-en-1 à cause d’une efficacité et d’une efficience améliorées (temps de
perfor-922
Review Articles/Brief Reviews
A review of approaches and techniques for lower
extremity nerve blocks
[Un bilan des approches et techniques pour les blocs nerveux du membre inférieur]
(Quang Hieu) De Tran MDFRCPC, Antonio Clemente MD, Roderick J. Finlayson MDFRCPC
From the Department of Anesthesia, Montreal General Hospital, McGill University, Montreal, Quebec, Canada.
Address correspondence to: Dr. De QH Tran, Montreal General Hospital, Department of Anesthesia, 1650 Ave Cedar, D10-144,
Montreal, Quebec H3G- 1A4, Canada. Phone: 514-934-1934, ext 43261; Fax: 514-934-4289; E-mail: [email protected] Competing interests: There were no direct funding sources associated with the preparation of this manuscript.
Accepted for publication August 8, 2007. Revision accepted August 20, 2007.
mance plus court, coût moindre). Pour un bloc du nerf sciatique, l’approche transglutéale constitue une méthode fiable. En raison d’un temps potentiellement plus court pour l’électrolocation du nerf sciatique et le positionnement du cathéter que par la voie transglutéale, l’approche subglutéale devrait également être prise en considération. Par rapport à l’électrolocation du nerf péronier, l’électrostimulation du nerf tibial pourrait offrir un taux de réussite plus élevé, particulièrement avec les abords transglutéal et latéral poplité. De plus, lors de la mise en place de blocs sciatique ou fémoral avec de petits volumes d’anesthésiques locaux, une tech-nique d’injection multiple devrait être utilisée.
Conclusion : Les comptes rendus publiés d’ERC fournissent des données probantes qui permettent de formuler des recomman-dations limitées en ce qui concerne les approches et techniques optimales pour l’anesthésie du membre inférieur. Des ERC bien conçues et exécutées avec soin sont requises, particulièrement à la lumière de nouvelles techniques d’écho-guidage.
H
ISTORICALLY, lower extremity nerveblocks have not been as widely used as brachial plexus blocks. This may be due to the fact that regional anesthesia of the lower limb requires blockade of several different nerves whereas neuraxial blocks reliably provide intra-operative anesthesia and postintra-operative analgesia with one puncture site. However, over the past decade, the increased use of low molecular weight heparins and the proven rehabilitative benefits associated with continu-ous femoral nerve blocks have led to a renewed interest amongst anesthesiologists to perform regional anesthe-sia for the lower limb.1–4 Despite this enthusiasm, there
still persist many variances in clinical methods for lower
extremity nerve blocks. Accordingly, a literature search of randomized clinical trials was undertaken to deter-mine the best available approaches and techniques for regional anesthesia of the lower limb. For the purposes of this narrative review, the term “approach” refers to the site where a neural structure can be accessed (anterior and posterior approaches for the lumbar plexus; pubic tubercle and inguinal approaches for the obturator nerve; perifemoral injection, transsartorial injection, paracondylar injection, infiltration around the medial tibial tuberosity, paravenous injection below the knee and infiltration around the medial malleolus for the saphenous nerve; parasacral approach for the sacral plexus; anterior, posterior transgluteal, posterior subgluteal, lateral midfemoral, lateral popliteal and posterior popliteal approaches for the sciatic nerve). On the other hand, the term “technique” refers to the modality (loss of resistance, neurostimulation, echogu-idance) or endpoints (type of neurostimulation, single
or multiple injections) needed to identify and anesthe-tize the nerve for a given approach.
Methods
Search strategy and selection criteria
The literature search for this review was conducted dur-ing the first week of May 2007, usdur-ing the MEDLINE (January 1966 to April 2007) and EMBASE (January 1980 to April 2007) databases. Medical subject head-ing (MeSH) terms “lumbosacral plexus”, “femo-ral nerve”, “obturator nerve”, “saphenous nerve”, “sciatic nerve”, “peroneal nerve” and “tibial nerve” were searched and combined with the MESH term “nerve block” using the operator “and”. Since “lum-bar plexus”, “psoas compartment”, “psoas sheath”, “sacral plexus”, “fascia iliaca”, “three-in-one”, “3-in-1”, “lateral femoral cutaneous”, “posterior femoral cutaneous”, “ankle” and “ankle block” do not exist as MESH terms, they were queried as keywords and combined with the MESH term “nerve block”. Furthermore, the results were limited to peer-reviewed reports of human studies published in the English lan-guage. From this initial search, only randomized con-trolled trials (RCTs) comparing different approaches or techniques of lower limb anesthesia were retained. After selecting the initial articles, we examined the respective reference lists, as well as our personal files,
for additional material. All studies containing an appropriately identified randomization process and active control groups were retained. No RCTs were excluded based on factors such as sample size justifica-tion, statistical power, blinding, definition of interven-tion allocainterven-tion or primary and secondary outcomes. However, non-randomized studies, observational case reports and cohort studies were excluded to avoid potential biases introduced by institutional practices.
Furthermore, only articles pertaining to approaches and techniques were retained. Dose finding studies and studies comparing local anesthetic agents (LA) or dealing with local anesthetic manipulation (thermoal-teration, alkalinization, addition of adjuncts, mixing, dose fractionation) exceeded the scope of this review. Articles pertaining to equipment (stimulating vs non stimulating perineural catheters) were also excluded. Finally, in RCTs comparing pain control provided by different nerve blocks in the setting of a specific surgi-cal procedure, only the data pertaining to the sensory and motor distributions provided by the blocks was retained for analysis.
Results
Our search criteria yielded 46 RCTs. Of these stud-ies (average sample size = 62 subjects), 54% provided
924 CANADIAN JOURNALOF ANESTHESIA sample size justification and 57% blinded assessment.
Only 28% provided data about allocation conceal-ment. Primary endpoints varied greatly: for instance, definitions of block success included surgical anes-thesia, sensory analgesia (patient cannot feel cold or pinprick) as well as combined sensory analgesia and motor block.
I LUMBAR PLEXUS, FEMORAL, LATERAL FEMORAL CUTANEOUS, OBTURATOR AND SAPHENOUS NERVE BLOCKS
Lumbar plexus block
APPROACHES
The lumbar plexus can be blocked with a posterior approach by injecting LA in a lumbar paravertebral location.5–8 Alternately Winnie et al.9 have suggested
that an inguinal, paravascular injection in the femoral perineural sheath (with concomittant distal manual compression and cephalad angulation of the needle) will lead to retrograde LA migration towards the lumbar plexus. Since the three main terminal branches (femoral, lateral femoral cutaneous and obturator nerves) of the lumbar plexus can be anesthetized with a single injection, this anterior approach is also called “3-in-1 block”.
Four RCTs (combined n = 250) have compared single shot anterior and posterior approaches with highly consistent results.7,10–12 At 30 min, both
meth-ods produced similar rates of sensory and motor block of the femoral nerve (93–100 and 73–100% of patients respectively).7,10,12 Two RCTs have reported a higher
success rate for blockade of the lateral femoral cutaneous nerve with the posterior approach (90–97 vs 50–53%;
P < 0.05)10,12 whereas another study found no
differ-ence (85–95%).7 All four RCTs reported significantly
better obturator block with the posterior approach: three RCTs noted an improved sensory block (77–80
vs 47–50%; P < 0.05)10–12 while two studies also found
a higher rate of motor block (63–100 vs 0–30%; P < 0.05).7,10 However, in 45 patients undergoing total
hip replacement, one study compared single shot lum-bar plexus and 3-in-1 blocks and failed to detect any difference in nerve block distribution.13
Two RCTs (combined n = 119) have compared con-tinuous posterior and anterior approaches for patients undergoing total knee replacement. While Morin et
al.14 reported similar performance time, onset and
success of obturator sensory blockade, Kaloul et al.15
found a better sensory block of the obturator nerve at 24 hr (P = 0.02). However both studies reported a sig-nificantly quicker onset (P = 0.0017) and better motor block of the obturator nerve at six hours (P = 0.006) with posterior lumbar plexus catheters.14,15
The unreliability of the anterior approach to block the obturator nerve may stem from the fact that LAs do not anesthetize the lateral femoral cutaneous and obturator nerves by proximal migration, but by lateral and medial diffusion respectively.1 Thus, with the
3-in-1 method, LA spread may occur preferentially in a lateral direction and spare the obturator nerve.12
Some authors have even advocated renaming the ante-rior approach “2-in-1 block”.16 This contention seems
to be supported by a RCT comparing 3-in-1 to direct obturator block: in 44 patients, Atanassof et al.17
observed that the latter method resulted in a denser motor block of the obturator nerve, as evidenced by a greater mean decrease from baseline in adductor compound muscle action potential testing (88.8 ± 21
vs 7.4 ± 19%; P < 0.05).
Techniques
In their original description of the anterior approach, Winnie et al.9 advocated using paresthesiae to locate
the femoral nerve. Seven subsequent RCTs have pro-posed modifications to this technique. In one study, compared to elicitation of paresthesiae, neurostimu-lation did not lead to an increased success rate.7 In
two RCTs (combined n = 100), compared to neuro-stimulation, ultrasonography provided a quicker onset (13–16 ± 6–14 vs 26–27 ± 12–16 min; P < 0.05) and a denser combined sensory block of the femoral, lateral femoral cutaneous and obturator nerves (4–15 ± 5–10 vs 21–27 ± 11–19% of sensation to pinprick compared to the unanesthetized contralateral limb; P < 0.05).18,19 A recent study has also reported better
blockade of all three nerves with echoguidance.11 In
1988, to improve obturator nerve block seen with the 3-in-1 technique, Dalens et al.20 introduced the fascia
iliaca compartment block, a method by which LA was injected immediately posterior to the fascia iliaca while firm compression was applied distal to the puncture site. In 120 children randomized to a (neurostimula-tion-guided) 3-in-1 or a (loss of resistance-guided) fas-cia iliaca compartment block, these authors reported a similar rate of complete sensory block for the femoral nerve (100%); however the fascia iliaca block resulted in improved blockade of the lateral femoral cutaneous and obturator nerves (92 vs 15% and 88 vs 13% of patients respectively; both P < 0.05).20 The same
com-parison was carried out in 100 adults. Again, despite a similar rate of femoral block (88–90%), the lateral femoral cutaneous nerve was more frequently anes-thetized with the fascia iliaca compartment technique (90 vs 62%; P < 0.05). However, sensory blockade of the obturator nerve showed no difference (38–52%).21
In a follow-up study, the same group of authors
pared perineural catheters inserted with the 3-in-1 and fascia iliaca techniques. The latter method resulted in a faster performance time (P < 0.05) and a lower mate-rial cost ($11 ± $2 vs $22 ± $3; P < 0.05). Despite similar blockade of the femoral and lateral femoral cutaneous nerves, the 3-in-1 technique produced a better sensory block of the obturator nerve at one, 24 and 48 hr.22 In 2006, using Winnie’s technique,9
Pham Dang et al.23 investigated the role of femoral
perineural sheath expansion for the insertion of stimu-lating catheters. In 60 patients randomly allocated to a bolus of 10 mL D5W through the needle or no bolus, they found that sheath expansion reduced the number of attempts (P = 0.007) and the resistance encountered (P = 0.01) during successful perineural catheter placement. However, no differences in spread were found when contrast was injected through the catheters.23
Different surface landmarks have been advocated for the posterior approach to the lumbar plexus.5–8
In a RCT comparing Winnie’s5 and Chayen’s6
land-marks using neurostimulation, Dalens et al.24 reported
that, in children, while both techniques achieved similarly successful block of the lumbar and sacral plexi (88–92% of patients), Chayen’s landmarks also led in 88% of cases to contralateral lumbar and sacral plexic anesthesia (through epidural LA spread). Comparing Winnie’s5 and Capdevila’s8 landmarks with
neuro-stimulation in 60 adults, Mannion et al.25 found
similar performance times (2.3–2.5 ± 1.5 min), similar patterns of block and comparable rates of epidural spread (33–40% of patients). Comparing Winnie’s5
or Chayen’s6 landmarks at the L4–5 level to Dekrey’s
landmarks7 at the L3 level, Parkinson et al.7 reported
similar blockade of the femoral, lateral femoral cutane-ous and obturator nerves at 30 min (95–100%). The incidence of epidural spread ranged from 4 to 25%. Interestingly, none of the 40 patients in this study pre-sented a complete block of a nerve originating from the sacral plexus.7
It must be noted that, while both Winnie5 and
Chayen6 advocated using loss of resistance to locate
the lumbar plexus in their original descriptions, all subsequent RCTs have employed neurostimulation for its identification.7,24,25 A formal study comparing
these two modalities or ultrasonography has not been undertaken. Furthermore, while preliminary imag-ing studies on volunteers seem to suggest a similar spread of contrast with Winnie’s5 and Chayen’s6
tech-niques, the comparative efficacy of catheters placed according to these different landmarks has not been investigated with RCTs.26 Finally, the optimal
loca-tion for placement of the needle (or catheter) tip
also requires further elucidation with RCTs: while Winnie’s5 and Chayen’s6 techniques (termed psoas
compartment blocks) aimed to position the needle tip in a fascial plane between the quadratus lumborum and psoas muscles, recent descriptions by Dekrey7 and
Capdevila8 (termed psoas sheath block) advocated
anesthetizing the roots of the lumbar plexus in the substance of the psoas muscle.
FEMORAL NERVE BLOCK
Some confusion exists in the literature regarding the terminology pertaining to femoral nerve blockade: despite specifically using Winnie’s description for the 3-in-1 block,9 some studies have nonetheless labelled
their technique “femoral nerve block”.13,14,23 Thus we
decided to include the results of these RCTs in the previous section. A review of the literature yielded only one RCT corresponding to our search criteria. When using a small dose of LA (12 mL of ropivacaine 0.75%), Casati et al.27 showed that, compared to a
single injection-technique, a triple-injection method (with electrolocation and anesthesia of the branches to the vastus medialis, intermedius and lateralis muscles) was preferable. Although block placement took less time with the single-injection technique (3.4 ± 1.2
vs 4.7 ± 1.7 min; P = 0.02), total preoperative time
was significantly shorter in patients receiving multiple injections because of a quicker onset time (10.0 ± 3.7
vs 30 ± 11 min; P < 0.001).
Femoral nerve block can be carried out either at the inguinal ligament or at the inguinal skin crease. Although cadaveric studies seem to suggest that the nerve is easier to locate at the crease, these two landmarks have not been compared with RCTs in humans.28 During electrolocation of the femoral
nerve, two responses are often encountered: sarto-rius muscle contraction (stimulation of the anterior branch of the femoral nerve) and quadriceps muscle contraction or “dancing patella” sign (stimulation of the posterior branch of the femoral nerve). Most authors advocate preferentially searching for the lat-ter response as articular branches derive from the posterior branch.1 Although sensible and anatomically
sound, this contention has not been confirmed with RCTs. Loss of resistance, elicitation of paresthesiae, neurostimulation and ultrasonography have all been investigated as adjunctive modalities for nerve local-ization in 3-in-1 block:7,11,18–22 although the results of
these studies can be extrapolated to femoral blockade, further RCTs are nonetheless required to investigate their use in the context of a specific femoral nerve block technique. Finally, as evidenced by the confu-sion in terminology, the difference between 3-in-1
926 CANADIAN JOURNALOF ANESTHESIA and femoral nerve block requires elucidation. In other
words, despite the unreliable block of the obturator nerve, it is not clearly established whether the 3-in-1 method is a different entity from the isolated femoral nerve block because of improved blockade of the lat-eral femoral cutaneous nerve.
LATERAL FEMORAL CUTANEOUS NERVE BLOCK In 20 volunteers randomized in a crossover study, Shannon et al.29 evaluated two techniques for
lat-eral femoral cutaneous nerve blockade: fan infiltra-tion and sensory neurostimulainfiltra-tion (aiming to elicit a paresthesia on the lateral thigh). The latter method achieved a higher success rate (100 vs 40%; P < 0.001). Furthermore electrolocation resulted in a quicker onset time (0.6 ± 0.2 vs 6.9 ± 6.1 min; P < 0.02) and a decreased rate of incidental femoral nerve block (5
vs 35% of patients; P = 0.02). No differences in the
extent of the block, performance time and procedural discomfort were noted.
OBTURATOR NERVE BLOCK
In 50 patients requiring an obturator block for knee arthroscopy, Choquet et al.30 compared the classic
approach (at the level of the pubic tubercle) to a new approach (at the level of the inguinal crease) and found that the latter method resulted in a decreased perfor-mance time (80 vs 120 sec; P < 0.05), less procedural discomfort (visual analogue score = 2 ± 1.4 vs 4 ± 1.7;
P < 0.001) and a lower incidence of minor
complica-tions such as vascular puncture and persistent groin pain (P < 0.05). Twenty minutes after application of the block, adductor strength decrease and cutaneous distributions of the obturator nerve block were not significantly different between the two groups. SAPHENOUS NERVEBLOCK
Several approaches for blockade of the saphenous nerve have been described: perifemoral injection, transsartorial injection, infiltration around the medial femoral condyle, infiltration around the medial tibial tuberosity, paravenous injection below the knee and infiltration around the medial malleolus. Techniques have included field blocks, loss of resistance and (sen-sory) neurostimulation. Four RCTs were reviewed, of which three compared approaches and one compared techniques.
In one RCT (n = 60) reported by Van der Wal et
al.,31 a transsartorial approach (using loss of
resis-tance) was compared to infiltrations around the medial femoral condyle and around the medial tibial tuberosity below the knee. The transsartorial approach achieved a higher success rate than infiltration below
the knee (80 vs 40% of patients; P < 0.05); it was also more successful than paracondylar infiltration (80
vs 65% of patients) but this failed to reach statistical
significance. In an effort to refine the transsartorial method, Comfort et al.32 compared loss of resistance
to (sensory) neurostimulation in a group of 25 volun-teers. The latter produced a higher success rate (100
vs 72% of patients; P < 0.05). However, procedural
pain scores, performance times and anesthesia-related times were also more elevated (1 vs 2 on a ten-point scale, 11 ± 5 vs 4 ± 1 min and 13 ± 7 vs 8 ± 2 min respectively; all P < 0.05). In a recent RCT, Benzon et
al.33 compared a neurostimulation-guided perifemoral
approach (4 cm below the inguinal crease) seeking a motor response in the vastus medialis or rectus femoris muscles, to a neurostimulation-guided transsartorial approach and three field blocks: paracondylar, below the knee and around the medial malleolus. These authors observed the following rates of blockade for the medial leg (above the ankle): 100% for the trans-sartorial approach, 70% for the perifemoral approach, 10% for paracondylar injection and 70% for below the knee infiltration. Because of the small number of subjects in the study (n = 10), statistical significance was only achieved when comparing paracondylar injection with the other groups. Assessment of the block below the ankle was more difficult because of the variable contribution of the superficial peroneal nerve. Interestingly, in the perifemoral group, despite approaching the saphenous nerve 4 cm below the inguinal crease, 70% of subjects still presented some degree of femoral motor blockade.
In 20 volunteers, De Mey et al.34 compared a blind
injection lateral and medial to the saphenous vein with one made below the knee (between the tibial tuberosity and the medial head of the gastrocnemius). The paravenous approach yielded a higher success rate (100% vs 33.3% of patients; P < 0.05). Performance time and procedural discomfort were not reported. INTERPRETATION
Compared to its anterior counterpart (3-in-1 block), the posterior approach to the lumbar plexus offers a higher success rate for single shot and continuous blocks because of improved anesthesia of the obtura-tor nerve. In children, Chayen’s technique for the posterior approach can lead to an increased incidence of epidural spread. In adults, no differences have been found between Winnie’s, Chayen’s, Dekrey’s and Capdevila’s landmarks. For the 3-in-1 block, ultraso-nography may be a superior technique to elicitation of paresthesiae and nerve stimulation. The fascia iliaca compartment block represents an interesting
alterna-tive to the 3-in-1 block: while providing a similarly efficacious block of the femoral nerve, it is associated with better anesthesia of the lateral femoral cutaneous and possibly of the obturator nerves. Furthermore, perineural catheters inserted with the fascia iliaca tech-nique may result in a quicker performance time and a lower material cost. Perineural sheath expansion with 10 mL D5W can reduce the resistance and attempts needed for successful catheter placement. For low volume femoral nerve blocks, a multiple-injection technique provides a shorter onset time.
Block of the lateral femoral cutaneous nerve can be carried out using sensory neurostimulation. Compared to the traditional fan infiltration technique, it leads to an improved onset time and success rate coupled with a reduced risk of incidental femoral nerve block.
A new inguinal approach for obturator nerve block has recently been described and compared to the tra-ditional method at the pubic tubercle. It was found to decrease the performance time, procedural discomfort and side effects.
The transsartorial and paravenous approaches rep-resent the best options for blockade of the saphenous nerve. Although sensory neurostimulation increases the efficacy of the transsartorial approach, it also results in increased pain scores as well as performance and anesthesia-related times.
II SACRAL PLEXUS, SCIATIC, TIBIAL, PERONEAL, POSTERIOR FEMORAL CUTA-NEOUS AND ANKLE NERVE BLOCKS
Sacral plexus
As described by Mansour,35 the parasacral approach
to the sacral plexus aims to anesthetize the latter just caudal to the posterior inferior iliac spine. In 150 patients undergoing lower limb surgery, using 20 mL of ropivacaine 0.75%, Cuvillon et al.36 compared this
method to a (double-injection) transgluteal sciatic nerve block: although the parasacral approach resulted in a quicker performance time (2 vs 5.5 min; P < 0.001), because of a slower onset (25 vs 15 min; P < 0.017), total anesthesia-related times (20–25 min) were similar between the two groups. No differences were noted in the success rates of sciatic and posterior femoral cutaneous nerve block.
Sciatic nerve
APPROACHES
Two RCTs (combined n = 178) have compared the transgluteal and subgluteal approaches for sciatic nerve block and reached similar conclusions: while no differences in success rates, onset and offset times were noted,37,38 the subgluteal approach was
associ-ated with quicker sciatic nerve electrolocation (32
vs 60 sec; P < 0.001) and less procedural pain (P <
0.001).37
Two RCTs (combined n = 158) have compared the transgluteal and posterior popliteal approaches for blockade of the sciatic nerve and found no differences in onset, offset and performance times. However, the procedure was significantly less painful with the popli-teal approach.39,40 While Kilpatrick et al.39 reported a
better success rate with the transgluteal approach (95
vs 45% of patients; P < 0.01), Fuzier et al.40 found no
difference between the two groups (94–98%).
Two RCTs (combined n = 100) have compared the transgluteal and lateral popliteal approaches: both studies found a longer onset for sensory and motor block with the latter.38,41 Taboada et al.41 also
reported a lower success rate with the lateral popliteal approach (68 vs 96% of patients; P < 0.05).
One RCT (n = 63) compared the lateral midfemoral and lateral popliteal approaches and reported no dif-ferences in performance time, procedural discomfort and quality as well as duration of sensory and motor blockade. The lateral midfemoral approach was associ-ated with shorter onset times for sensory block of the tibial nerve (5 vs 10 min; P = 0.016) and for motor block of the tibial and peroneal nerves (5 vs 15 min; P = 0.03 and 6 vs 15 min; P = 0.009 respectively).42
One RCT (n = 59) compared the lateral midfemo-ral and anterior approaches and reported no differ-ences in performance time (4.9–6.1 min), success rate (77–79%), onset time (18–19 min) and block duration (373–506 min).43 Another RCT (n = 50)
compared the posterior popliteal and lateral popliteal approaches and found similar success rates. The pos-terior approach required fewer attempts to localize the sciatic nerve.44
Of all the studies evaluated, only one compared dif-ferent approaches for sciatic nerve block in a pediatric population. Dalens et al.45 randomized 180 children
undergoing lower extremity surgery to an anterior, a posterior transgluteal and a lateral midfemoral approach. No differences in overall success rate (82– 97%) and block duration were noted. The distribution of anesthesia in the lower extremity was similar and included not only territories supplied by the sciatic nerve but also those supplied by the posterior femoral cutaneous nerve. However, the posterior approach was associated with a higher success rate on the first attempt compared to the lateral and anterior approaches (88 vs 78 and 62% respectively; both P < 0.05). In turn, the lateral approach also achieved a higher first-pass success rate than the anterior approach (P < 0.05).
928 CANADIAN JOURNALOF ANESTHESIA perineural catheter placement using the subgluteal
and posterior popliteal approaches. In one study, more attempts were necessary to achieve successful catheter placement with the latter method.46 The rate of
cath-eter occlusion or dislodgement did not differ between groups.47 In the literature, no other RCTs were found
comparing approaches for placement of sciatic peri-neural catheters.
TECHNIQUES
In 20 patients, using new landmarks for the anterior approach (puncture site 2.5 cm medial to the femoral artery and 2.5 cm distal to the inguinal crease), Van Elstraete et al.48 compared placement of the patient’s
leg in a neutral position or in external rotation. These authors found that, with the latter approach, the sci-atic nerve was more quickly electrolocated (46 ± 25
vs 79 ± 53 sec; P < 0.006). However success rates,
distances from skin to nerve, numbers of attempts required and side effects were similar.
Two RCTs (combined n = 150) using the posterior transgluteal approach compared a single to a double-injection technique, in which the tibial and peroneal components of the sciatic nerve were independently electrostimulated and anesthetized. In both studies, 20 mL of LA (ropivacaine 0.75% or a mix of lidocaine 1% and tetracaine 0.2%) were used for the two groups. The findings were consistent. A double-injection tech-nique produced a higher success rate at 45 min (75– 100 vs 55–80% of patients; P < 0.05).36,49 Although
associated with a longer performance time (5.5 vs 3 min; P = 0.001), it also resulted in a quicker onset (15
vs 25 min; P < 0.017). Thus the total
anesthesia-relat-ed times were not different between the two groups (20–25 min).49 In 80 patients undergoing hallux
val-gus surgery, Taboada et al.50 compared plantar flexion
(tibial nerve stimulation) to dorsiflexion (peroneal
nerve stimulation) as the stimulatory response guiding a single-injection technique. These authors observed a higher success rate with plantar flexion (87.5 vs 55%: P < 0.05). Furthermore, the latter also produced shorter onset times for complete sensory and motor block (10 ± 10 vs 20 ± 11 min and 13 ± 10 vs 24 ± 12 min respectively; both P < 0.05). Taboada et al.50
attrib-uted the improved success and onset seen with plantar flexion to the fact that the tibial nerve is the larger of the two sciatic neural components and thus requires more LA to be deposited in its vicinity.
It must be noted that the landmarks used for the transgluteal approach in all the preceding studies originate either from Labat’s51 or Winnie’s5
descrip-tions; despite their widespread use and popularity, these two methods have never been formally
com-pared with RCTs, nor have they been determined to be interchangeable.
One RCT (n = 50) has compared single and dou-ble-injection techniques for the posterior subgluteal approach. In both groups, 30 mL of ropivacaine 0.75%
were used. Despite a similar success rate (92–96%), performance time (2.4–3.1 min) and block duration, Taboada et al.52 reported that the double-injection
technique produced a faster onset of complete sensory and motor blockade (7.4 vs 12.5 min and 12.3 vs 18.8 min respectively; both P < 0.001). However, the sin-gle-injection method caused less procedural discom-fort (P = 0.013). Although preliminary works suggest that inversion constitutes the best neurostimulatory response for the subgluteal approach, this finding has not been validated with RCTs.53
Two studies have attempted to determine the best technique for the lateral midfemoral approach. In one RCT (n = 50), a proximal (20 cm distal to the greater trochanter) and distal puncture site (30 cm distal to the greater trochanter) were compared in patients receiv-ing 20 mL of mepivacaine 1.5%.54 Taboada et al.54
observed, with the proximal method, a higher success rate (88 vs 56%; P < 0.05) and a faster onset of com-plete sensory and motor blockade (12 ± 7 vs 19 ± 9 min and 15 ± 8 vs 23 ± 9 min respectively; both P < 0.05) because of a quicker sensory and motor block of the peroneal component. In the second RCT, adjunctive neurostimulation was compared to neurostimulation combined with echoguidance.55 In 61 patients
under-going foot and ankle surgery, Domingo-Triado et al.55
found that, with the combination of the two modali-ties, fewer attempts were required (1 vs 2; P = 0.001) and a denser sensory block was achieved (P = 0.01). However performance, onset and offset times were not significantly different between the two groups.
One RCT (n = 60), using 25 mL of mepivacaine 1.5%, compared single and double-injection tech-niques for the posterior popliteal approach and found similar success rates (77–87% of patients) as well as onset times for sensory block (21.9–22.1 min). Despite a quicker performance time with the single-injection technique (4.6 ± 2.8 vs 5.9 ± 3.1 min; P = 0.03), total anesthesia-related times were similar. However, patients receiving a single injection reported fewer paresthesiae (17 vs 40% of patients; P = 0.04).56
Although observational studies have suggested that the optimal evoked motor response for posterior pop-liteal sciatic blockade is inversion, this finding requires further validation with RCTs.57
Two RCTs have compared single and double-injec-tion techniques for the lateral popliteal approach with conflicting results.58,59 In one RCT (n = 50), using
20 mL of an equal mix of lidocaine 2% and bupiva-caine 0.5% and seeking foot inversion as the preferred
response for the single-injection group, Paqueron et
al.58 observed a lower success rate (54 vs 88%; P =
0.007) with the latter. Onset times for sensory and motor block were similar. In contrast, Arcioni et al.59
randomized 96 patients undergoing foot surgery to a lateral popliteal sciatic block using a single-injection technique seeking tibial nerve stimulation, a single injection seeking peroneal nerve stimulation (dorsi-flexion or eversion) or a double-injection technique. The total volume administered was 30 mL of ropiva-caine 0.75%. These authors reported that, compared to a double-injection technique, the single-injection method with tibial nerve electrolocation resulted in a similar performance time (400–487 sec) and success rate (94%). However the onset time for sensory block-ade was shorter with the single-injection technique (14 ± 7 vs 21 ± 14 min; P < 0.05). Patients receiving a single injection with peroneal nerve electrolocation displayed a lower success rate than the other two groups (75%).59 In another RCT (n = 30), Taboada
Muniz et al.60 also concluded that, compared to
plan-tar flexion, dorsiflexion resulted in a lower success rate (33 vs 93%; P < 0.05). In addition, onset times for sensory and motor block were slower as well (24.3 ± 5.1 vs 16.6 ± 5.1 min and 28.1 ± 5.0 vs 20.1 ± 5.1 min; both P < 0.05).
TIBIAL NERVE BLOCK
In a study of 135 patients, Doty et al.61 compared
three methods to anesthetize the posterior tibial nerve: blind infiltration around the medial malleolus, neurostimulation-guided injection around the medial malleolus or neurostimulation-guided injection 7 cm
above the latter, in the subfascial plane between the flexor hallucis longus and flexor digitorum longus tendons. Compared to fan infiltration, electrolocation consistently resulted in a quicker onset and a higher success rate (93–100 vs 75.5%; P = 0.02). Posterior tibial nerve block with electrolocation at the distal site produced a quicker onset than at the proximal site (8
vs 15 min; P = 0.05).
PERONEAL, POSTERIOR FEMORAL CUTANEOUS AND ANKLE NERVE BLOCK
The optimal approaches and techniques for these blocks have not been investigated with RCTs.
INTERPRETATION
The posterior transgluteal approach is the most widely used approach for sciatic nerve blockade.37
Review of the literature suggests that it may also be
one of the most reliable methods. The transgluteal approach is superior in efficacy (success rate) and efficiency (onset) to its posterior and lateral popli-teal counterparts. In children, it provides a higher rate of success on the first attempt than the lateral and anterior approaches. Furthermore it may even be comparable to a more proximal method like the parasacral approach. However, by allowing quicker sciatic nerve electrolocation, the recently introduced posterior subgluteal approach offers an advantage over the traditional transgluteal method. For the place-ment of sciatic perineural catheters, fewer attempts are required with the subgluteal than the posterior popli-teal approach. RCTs comparing other approaches for continuous sciatic catheters are lacking.
The sciatic nerve is composed of two distinct but contiguous neural structures: the tibial and peroneal nerves. To increase the efficacy of sciatic block, many authors have advocated separately electrolocating and anesthetizing the two nerves. In the literature, three RCTs (pertaining to the transgluteal and lateral popli-teal approaches) have demonstrated an improved suc-cess rate using a double-injection technique.36,49,58 In
contrast, three other RCTs (pertaining to the subglu-teal, posterior and lateral popliteal approaches) failed to detect any such difference.52,56,59 Although a review
of the optimal LA dose required for sciatic nerve blockade exceeds the scope of this paper, it is interest-ing to note that the studies that found an improved success rate with two injections used a total dose of 20 mL of LA. In contrast, those that did not employed a larger volume (25–30 mL).
Of the two bundles, the tibial nerve is larger in size: thus it would appear logical that LA deposition in its vicinity (in the context of a single-injection technique) would lead to a more successful block than injection around the peroneal nerve. Although non-random-ized studies pertaining to the subgluteal and posterior popliteal approaches have suggested that inversion or plantar flexion should be preferentially sought during neurostimulation,53,57 only three RCTs (pertaining to
the transgluteal and lateral popliteal approaches) have validated this finding.50,59,60
Ultrasonography, in combination with neurostimu-lation, has been successfully used as an adjunct in one RCT pertaining to the lateral midfemoral approach.55
Further RCTs are required to determine its role in other approaches. Finally, the best method for anes-thesia of the posterior tibial nerve is a neurostimula-tion-guided injection around the medial malleolus. LIMITATIONS
930 CANADIAN JOURNALOF ANESTHESIA
this review to RCTs published in the English lan-guage. Although such a restriction may constitute a methodological limitation, we believe that its impact on overall conclusions is minimal: expansion of our search criteria (using the same databases and time periods) to languages other than English only yielded an additional five RCTs.62–66 Furthermore, no attempt
was made to produce a meta-analysis. In our view, given the wide array of approaches and techniques
commonly used for lower extremity anesthesia, patient enrolment would have been insufficient for many approaches and techniques to support a systematic pooling of data. The heterogeneous definitions of endpoints like block success would also make this task very difficult. Finally, all RCTs published in English were kept for the analysis: no studies were excluded based on factors such as sample size justification, statistical power, blinding, definition of interven-TABLE Areas pertaining to lower extremity nerve blocks warranting further investigation with randomized controlled trials Posterior approach for lumbar plexus block • Reliability of Dekrey’s and Capdevila’s landmarks for pediatric patients
• Comparison between loss of resistance and neurostimulation for localization of the lumbar plexus
• Comparison between Winnie’s, Chayen’s, Dekrey’s and Capdevila’s landmarks for catheter placement
• Optimal position for needle and catheter tips: between the quadratus lumborum and psoas vs inside the psoas muscle
• Perineural sheath expansion for the placement of lumbar plexic catheters 3-in-1 block • Comparison between 3-in-1 and isolated femoral nerve blocks
Femoral nerve block • Comparison between elicitation of paresthesiae and neurostimulation as techniques for nerve localization
• Comparison between single and multiple-injection techniques for local anesthetic volumes superior to 12 mL
• Optimal surface landmarks for femoral nerve electrolocation • Optimal evoked motor response: sartorial vs quadricipital contraction
Sacral plexus block • Comparison between the sacral plexus block and the posterior subgluteal approach to the sciatic nerve
• Perineural sheath expansion for the placement of sacral plexic catheters Sciatic nerve block • Comparison between the subgluteal and non-transgluteal approaches (anterior,
lateral midfemoral and lateral popliteal)
• Comparison between approaches (other than posterior, lateral and anterior) for pediatric patients
• Comparison between approaches (other than subgluteal and posterior popliteal) for the placement of sciatic catheters
• Comparison between a single-injection technique using 25–30 mL LA and a double-injection technique using 20 mL LA
• Optimal evoked motor response for methods other than the transgluteal and lateral popliteal approaches
• Perineural sheath expansion for the placement of sciatic catheters LA = local anesthetic agents.
tion allocation or primary and secondary outcomes. This may represent a limitation to our review as it may serve to overemphasize evidence derived from “weaker” RCTs.
Conclusions
Compared to the 3-in-1 block, the posterior approach to the lumbar plexus is more reliable when anesthe-sia of the obturator nerve is required. In adults, no differences have been found between the different landmarks described for the posterior approach. In children, Chayen’s technique is associated with an increased incidence of epidural spread. The fascia iliaca compartment block may also represent a better alternative than the 3-in-1 block because of improved efficacy (better anesthesia of the lateral femoral cuta-neous and obturator nerves) and efficiency (quicker performance time, lower cost).
For blockade of the sciatic nerve, the classic transgluteal approach constitutes a reliable method. However, because of the short time required for sci-atic nerve electrolocation and placement of perineural catheters, the subgluteal approach should also be con-sidered. Compared to electrolocation of the peroneal nerve, electrostimulation of the tibial nerve may offer a higher success rate especially with the transgluteal and lateral popliteal approaches. Furthermore, when performing sciatic and femoral nerve blocks with low LA volumes (20 and 12 mL respectively), a multiple-injection technique should be preferentially used.
For blockade of the lateral femoral cutaneous nerve, sensory neurostimulation is more reliable than fan infiltration. Compared to the traditional method, a new inguinal approach for obturator nerve block has been shown to decrease the performance time, patient discomfort and side effects. The transsartorial and paravenous approaches represent the best options for blockade of the saphenous nerve. The best method for anesthesia of the posterior tibial nerve is a neurostimu-lation-guided injection around the medial malleolus.
A critical survey of the available RCTs can pro-vide an effective tool to establish the most effective approaches and techniques for lower limb anesthesia. Despite current best evidence, many issues regarding lower extremity nerve blocks remain unresolved and require further elucidation through well designed and meticulously conducted RCTs (Table). Furthermore, although promising, the role of adjunctive ultrasonog-raphy needs to be better and systematically defined.
References
1 Enneking FK, Chan V, Greger J, Hadzic A, Lang SA, Horlocker TT. Lower-extremity peripheral nerve
blockade: essentials of our current understanding. Reg Anesth Pain Med 2005; 30: 4–35.
2 Singelyn FJ, Deyaert M, Joris D, Pendeville E, Gouverneur JM. Effects of intravenous
patient-con-trolled analgesia with morphine, continuous epidural analgesia, and continuous three-in-one block on post-operative pain and knee rehabilitation after unilateral total knee arthroplasty. Anesth Analg 1998; 87: 88–92.
3 Capdevila X, Barthelet Y, Biboulet P, Ryckwaert Y, Rubenovitch J, d’Athis F. Effects of perioperative
analgesic technique on the surgical outcome and duration of rehabilitation after major knee surgery. Anesthesiology 1999; 91: 8–15.
4 Barrington MJ, Olive D, Low K, Scott DA, Brittain J, Choong P. Continuous femoral nerve blockade or
epi-dural analgesia after total knee replacement: a prospec-tive randomized controlled trial. Anesth Analg 2005; 101: 1824–9.
5 Winnie AP, Ramamurthy S, Durrani Z, Radonjic R.
Plexus blocks for lower extremity surgery: new answers to old problems. Anesthesiol Rev 1974; 1: 11–6.
6 Chayen D, Nathan H, Chayen M. The psoas
compart-ment block. Anesthesiology 1976; 45: 95–9.
7 Parkinson SK, Mueller JB, Little WL, Bailey SL. Extent
of blockade with various approaches to the lumbar plexus. Anesth Analg 1989; 68: 243–8.
8 Capdevila X, Macaire P, Dadure C, et al. Continuous
psoas compartment block for postoperative analgesia after total hip arthroplasty : new landmarks, technical guidelines, and clinical evaluation. Anesth Analg 2002; 94: 1606–13.
9 Winnie AP, Ramamurthy S, Durrani Z. The inguinal
paravascular technic of lumbar plexus anesthesia: the “3-in-1 block”. Anesth Analg 1973; 52: 989–96.
10 Tokat O, Turker YG, Uckunkaya N, Yilmazlar A. A
clinical comparison of psoas compartment and inguinal paravascular blocks combined with sciatic nerve block. J Int Med Res 2002; 30: 161–7.
11 Ali AM, Tahoun HM, Ahmed AA, Hussein KH.
Comparative study between the analgesic efficacies of nerve stimulator-guided 3-in-1 block, ultrasonograph-ic-guided 3-in-1 block and posterior approach lumbar plexus block following total hip arthroplasty. Eg J Anaesth 2003; 19: 39–43.
12 Ganidagli S, Cengiz M, Baysal Z, Baktiroglu L, Sarban
S. The comparison of two lower extremity block
tech-niques combined with sciatic block: 3-in-1 femoral block vs. psoas compartment block. Int J Clin Pract 2005; 59: 771–6.
13 Biboulet P, Morau D, Aubas P, Bringuier-Branchereau S, Capdevila X. Postoperative analgesia after total-hip
arthroplasty: comparison of intravenous patient-con-trolled analgesia with morphine and single injection of
932 CANADIAN JOURNALOF ANESTHESIA femoral nerve or psoas compartment block. A
prospec-tive, randomized, double-blind study. Reg Anesth Pain Med 2004; 29: 102–9.
14 Morin AM, Kratz CD, Eberhart LH, et al.
Postoperative analgesia and functional recovery after total-knee replacement: comparison of a continuous posterior lumbar plexus (psoas compartment) block, a continuous femoral nerve block, and the combination of a continuous femoral and sciatic nerve block. Reg Anesth Pain Med 2005; 30: 434–45.
15 Kaloul I, Guay J, Cote C, Fallaha M. The posterior lumbar plexus (psoas compartment) block and the three-in-one femoral nerve block provide similar post-operative analgesia after total knee replacement. Can J Anesth 2004; 51: 45–51.
16 Spillane WF. 3-in-1 blocks and continuous 3-in-1
blocks. Reg Anesth 1992; 17: 175–6. 17 Atanassoff PG, Weiss BW, Brull SJ, et al.
Electromyographic comparison of obturator nerve block to three-in-one block. Anesth Analg 1995; 81: 529–33.
18 Marhofer P, Schrogendorfer K, Koinig H, Kapral S, Weinstabl C, Mayer N. Ultrasonographic guidance
improves sensory block and onset time of three-in-one blocks. Anesth Analg 1997; 85: 854–7.
19 Marhofer P, Schrogendorfer K, Wallner T, Koinig H, Mayer N, Kapral S. Ultrasonographic guidance reduces
the amount of local anesthetic for 3-in-1 blocks. Reg Anesth Pain Med 1998; 23: 584–8.
20 Dalens B, Vanneuville G, Tanguy A. Comparison of the
fascia iliaca compartment block with the 3-in-1 block in children. Anesth Analg 1989; 69: 705–13.
21 Capdevila X, Biboulet P, Bouregba M, Barthelet Y, Rubenovitch J, d’Athis F. Comparison of the
three-in-one and fascia iliaca compartment blocks in adults: clinical and radiographic analysis. Anesth Analg 1998; 86: 1039–44.
22 Morau D, Lopez S, Biboulet P, Bernard N, Amar J, Capdevila X. Comparison of continuous 3-in-1 and
fascia iliaca compartment blocks for postoperative analgesia: feasibility, catheter migration, distribution of sensory block, and analgesic efficacy. Reg Anesth Pain Med 2003; 28: 309–14.
23 Pham Dang C, Guilley J, Dernis L, et al. Is there any need for expanding the perineural space before catheter placement in continuous femoral nerve blocks? Reg Anesth Pain Med 2006; 31: 393–400.
24 Dalens B, Tanguy A, Vanneuville G. Lumbar plexus
block in children: a comparison of two procedures in 50 patients. Anesth Analg 1988; 67: 750–8.
25 Mannion S, O’Callaghan S, Walsh M, Murphy DB, Shorten GD. In with the new, out with the old?
Comparison of two approaches for psoas compartment
block. Anesth Analg 2005; 101: 259–64.
26 Mannion S, Barrett J, Kelly D, Murphy DB, Shorten GD. A description of the spread of injectate after psoas
compartment block using magnetic resonance imaging. Reg Anesth Pain Med 2005; 30: 567–71.
27 Casati A, Fanelli G, Beccaria P, et al. The effects of the single or multiple injection technique on the onset time of femoral nerve blocks with 0.75% ropivacaine. Anesth Analg 2000; 91: 181–4.
28 Vloka JD, Hadzic A, Drobnik L, Ernest A, Reiss W, Thys DM. Anatomical landmarks for femoral nerve block: a
comparison of four needle insertion sites. Anesth Analg 1999; 89: 1467–70.
29 Shannon J, Lang SA, Yip RW, Gerard M. Lateral
femo-ral cutaneous nerve block revisited. A nerve stimulator technique. Reg Anesth 1995; 20: 100–4.
30 Choquet O, Capdevila X, Bennourine K, Feugeas JL,
Bringuier-Branchereau S, Manelli JC. A new inguinal
approach for the obturator nerve block: anatomical and randomized clinical studies. Anesthesiology 2005; 103: 1238–45.
31 van der Wal M, Lang SA, Yip RW. Transsartorial
approach for saphenous nerve block. Can J Anaesth 1993; 40: 542–6.
32 Comfort VK, Lang SA, Yip RW. Saphenous nerve anaesthesia - a nerve stimulator technique. Can J Anaesth 1996; 43: 852–7.
33 Benzon HT, Sharma S, Calimaran A. Comparison of
the different approaches to saphenous nerve block. Anesthesiology 2005; 102: 633–8.
34 De Mey JC, Deruyck LJ, Cammu G, De Baerdemaeker LE, Mortier EP. A paravenous approach for the
saphe-nous nerve block. Reg Anesth Pain Med 2001; 26: 504–6.
35 Mansour NY. Reevaluating the sciatic nerve block: another landmark for consideration. Reg Anesth 1993; 18: 322–3.
36 Cuvillon P, Ripart J, Jeannes P, et al. Comparison of the parasacral approach and the posterior approach, with single- and double-injection techniques, to block the sciatic nerve. Anesthesiology 2003; 98: 1436–41. 37 di Benedetto P, Bertini L, Casati A, Borghi B, Albertin
A, Fanelli G. A new posterior approach to the sciatic
nerve block: a prospective, randomized comparison with the classic posterior approach. Anesth Analg 2001; 93: 1040–4.
38 Taboada M, Alvarez J, Cortes J, et al. The effects of three different approaches on the onset time of sciatic nerve blocks with 0.75% ropivacaine. Anesth Analg 2004; 98: 242–7.
39 Kilpatrick AW, Coventry DM, Todd JG. A comparison
of two approaches to sciatic nerve block. Anaesthesia 1992; 47: 155–7.
40 Fuzier R, Hoffreumont P, Bringuier-Branchereau S, Capdevila X, Singelyn F. Does the sciatic nerve
approach influence thigh tourniquet tolerance during below-knee surgery? Anesth Analg 2005; 100: 1511–4.
41 Taboada M, Rodriguez J, Alvarez J, Cortes J, Gude F, Atanasoff PG. Sciatic nerve block via posterior
Labat approach is more efficient than lateral popli-teal approach using a double-injection technique: a prospective, randomized comparison. Anesthesiology 2004; 101: 138–42.
42 Triado VD, Crespo MT, Aguilar JL, Atanasoff PG, Palanca JM, Moro B. A comparison of lateral popliteal
versus lateral midfemoral sciatic nerve blockade using ropivacaine 0.5%. Reg Anesth Pain Med 2004; 29: 23–7.
43 Fuzier R, Fuzier V, Albert N, et al. The sciatic nerve
block in emergency settings: a comparison between a new anterior and the classic lateral approaches. Med Sci Monit 2004; 10: CR563–7.
44 Hadzic A, Vloka JD. A comparison of the posterior
versus lateral approaches to the block of the sciatic nerve in the popliteal fossa. Anesthesiology 1998; 88: 1480–6.
45 Dalens B, Tanguy A, Vanneuville G. Sciatic nerve
blocks in children: comparison of the posterior, ante-rior, and lateral approaches in 180 pediatric patients. Anesth Analg 1990; 70: 131–7.
46 Taboada M, Rodriguez J, Valino C, et al. A prospective,
randomized comparison between the popliteal and sub-gluteal approaches for continuous sciatic nerve block with stimulating catheters. Anesth Analg 2006; 103: 244–7.
47 di Benedetto P, Casati A, Bertini L, Fanelli G, Chelly JE. Postoperative analgesia with continuous sciatic
nerve block after foot surgery: a prospective, random-ized comparison between the popliteal and subgluteal approaches. Anesth Analg 2002; 94: 996–1000. 48 Van Elstraete AC, Poey C, Lebrun T, Pastureau F. New
landmarks for the anterior approach to the sciatic nerve block: imaging and clinical study. Anesth Analg 2002; 95: 214–8.
49 Bailey SL, Parkinson SK, Little WL, Simmerman SR.
Sciatic nerve block. A comparison of single versus dou-ble injection technique. Reg Anesth 1994; 19: 9–13.
50 Taboada M, Atanassoff PG, Rodriguez J, et al. Plantar
flexion seems more reliable than dorsiflexion with Labat’s sciatic nerve block: a prospective, randomized comparison. Anesth Analg 2005; 100: 250–4.
51 Labat G. Regional Anesthesia: Its Technic and Clinical
Application. Philadelphia, PA: W.B. Saunders; 1922.
52 Taboada M, Alvarez J, Cortes J, Rodriguez J, Atanassoff PG. Is a double-injection technique superior to a single
injection in posterior subgluteal sciatic nerve block?
Acta Anaesthesiol Scand 2004; 48: 883–7.
53 Sukhani R, Nader A, Candido KD, et al. Nerve
stimu-lator-assisted evoked motor response predicts the laten-cy and success of a single-injection sciatic block. Anesth Analg 2004; 99: 584–8.
54 Taboada M, Rodriguez J, Del Rio S, et al. Does the site
of injection distal to the greater trochanter make a dif-ference in lateral sciatic nerve blockade? Anesth Analg 2005; 101: 1188–91.
55 Domingo-Triado V, Selfa S, Martinez F, et al. Ultrasound guidance for lateral midfemoral sciatic nerve block: a prospective, comparative, randomized study. Anesth Analg 2007; 104: 1270–4.
56 March X, Pineda O, Garcia MM, Carames D, Villalonga A. The posterior approach to the sciatic
nerve in the popliteal fossa: a comparison of single- versus double-injection technique. Anesth Analg 2006; 103: 1571–3.
57 Benzon HT, Kim C, Benzon HP, Silverstein ME, et al.
Correlation between evoked motor response of the sci-atic nerve and sensory blockade. Anesthesiology 1997; 87: 547–52.
58 Paqueron X, Bouaziz H, Macalou D, et al. The lateral
approach to the sciatic nerve at the popliteal fossa: one or two injections? Anesth Analg 1999; 89: 1221–5.
59 Arcioni R, Palmisani S, Della Rocca M, et al. Lateral
popliteal sciatic nerve block: a single injection targeting the tibial branch of the sciatic nerve is as effective as a double-injection technique. Acta Anaesthesiol Scand 2007; 51: 115–21.
60 Taboada Muniz M, Alvarez J, Cortes J, Rodriguez J, Atanassoff PG. Lateral approach to the sciatic nerve
block in the popliteal fossa: correlation between evoked motor response and sensory block. Reg Anesth Pain Med 2003; 28: 450–5.
61 Doty R Jr, Sukhani R, Kendall MC, et al. Evaluation
of a proximal block site and the use of nerve-stimula-tor guided needle placement for posterior nerve block. Anesth Analg 2006; 103: 1300–5.
62 Taboada M, Lorenzo D, Oliveira J, et al. Comparison of 4 techniques for internal saphenous nerve block (Spanish). Rev Esp Anestesiol Reanim 2004; 51: 509– 14.
63 Kaiser H, Niesel HC, Klimpel L. Influence of minimum
current for peripheral nerve stimulation on the latency and success rate of sciatic blockade (German). Reg Anaesth 1988; 11: 92–7.
64 Domingo Triado V, Cabezudo de la Muela L, Crespo Pociello MT, et al. Sciatic nerve block with 1%
mepiva-caine for foot surgery: posterior versus lateral approach to the popliteal fossa (Spanish). Rev Esp Anestesiol Reanim 2004; 51: 70–4.
934 CANADIAN JOURNALOF ANESTHESIA
Barbeito Vilarino MJ, Bonome Gonzalez C, Coblan Llamas JM. Popliteal fossa sciatic nerve block for
ambulatory hallux valgus surgery: comparison of lateral and posterior approaches (Spanish). Rev Esp Anestesiol Reanim 2005; 52: 4–8.
66 Palacios ME, Rufino J, Santiago FM, et al. Sciatic block
at the level of the popliteal fossa. a comparison of two approaches (Spanish). Rev Soc Esp Dolor 2005; 12: 264–8.
